This invention relates to a check valve assembly for closing the upper end of a vent pipe to prevent the escape of pollutant gas, and more particularly to such a valve assembly which is automatic in operation.
A principal object of this invention is to provide a means for controlling the venting of the plumbing system, in residences or other structures, which will prevent the venting of sewer gas along with its inherent objectionable odor and undesirable pollutants into the atmosphere, and which will eliminate the necessity for expensive and unsightly vent pipes which project upwardly from the roofs of residences or other building structures.
Another object of this invention is to provide a relatively inexpensive and effective check valve assembly which can be readily mounted to the upper end of a vent pipe in a structure, preferably in the attic spaces of such structure, or in any other suitable location, and which will perform the desired venting function for the plumbing system.
A further object of this invention is to provide a valve assembly which will act automatically to maintain the vent pipe closed to prevent venting of undesirable gases and fumes to the atmosphere, and which will automatically allow fresh air from the atmosphere to enter the plumbing system each time a suction or vacuum is created in the system when liquids are flushed through the waste pipes following use of connected plumbing fixtures.
Still another object of this invention is to provide such a valve assembly of simple construction enabling economic manufacture, and yet which is effective for the intended purpose.
These objects are accomplished in a valve assembly which includes an elongated thin walled cylindrical sleeve dimensioned to be clamped over the end of a vent pipe, and having longitudinal slots opening to said inner end to allow diameter variation. A resilient annular gasket, dimensioned for a snug fit within the sleeve slotted end, provides a seal between the sleeve and pipe. A valve plate is mounted on a transverse pivot shaft, with a major portion of the plate disposed on one side of the shaft and a minor portion disposed on the other side; and the pivot shaft is mounted transversely of the sleeve intermediate its ends and offset from the sleeve axis. Seat means mounted on the sleeve define a seating plane in which the valve plate closes the sleeve, with the seat means being disposed to permit inward swinging of the plate major portion and outward swinging of the plate minor portion. Means coupled to the valve plate urges rotation into the seating plane.